The removal of commercial messages from received television signals during the home recording of television programs has been a goal of the video equipment industry for many years. Accordingly, several systems have been proposed in the prior art which attempt to achieve that objective. However, attempts in the prior art to provide a reliable system for automatically detecting the occurrence of commercial breaks in received television signals have been only partially successful.
It is known that just prior to a commercial message, the amplitude of the video signal of the television signal drops towards the black level, and the amplitude of the audio fades towards the zero sound level. The prior art systems usually include a detector circuit which detects each such drop in the video and audio components of the received television signal and which produces an output pulse in response thereto. The prior art systems also usually include a timing circuit which is triggered by each pulse from the detector circuit to produce an editing control signal which continues for the duration of a standard commercial break. It is usual prior art practice to apply the editing control signal to the remote pause control of the video tape recorder so that the video tape recorder is hopefully stopped for the duration of the commercial messages and does not record the commercial messages.
However, the prior art systems are subject to a major disadvantage. Namely, should a drop occur in the amplitude of the video and audio content of the television program itself, the prior art detector circult treats the drop as the start of a commercial message, so that the ensuing portion of the television program is not recorded, and portions of the program are lost. Also, in the prior art systems the duration of the editing signal is an arbitrarily fixed time and portions of the program following a commercial break are often inadvertently blanked out.
The present invention has overcome the shortcomings of the prior art by introducing an affordable apparatus which when connected to an existing video tape recorder, will control a program delay system, such that valid determinations can be made between unwanted and wanted television program material prior to recording.
This system of the invention has four major elements:
(1) Information processing to identify the unwanted material.
(2) Tape delay system to provide sequential storage and delay of all incoming material so that valid determinations can be made between desired and unwanted program material.
(3) A control system to coordinate the information processing choices and the editing actions.
(4) A means to edit or delete or stop the information feed from the system to the video recorder or other instrumentality.